81900013 has 8 divisors (see below), whose sum is σ = 92842400. Its totient is φ = 71620848.

The previous prime is 81899977. The next prime is 81900017. The reversal of 81900013 is 31000918.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 81900013 - 2⁹ = 81899501 is a prime.

It is a super-2 number, since 2×81900013² = 13415224258800338, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81900017) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 165543 + ... + 166036.

It is an arithmetic number, because the mean of its divisors is an integer number (11605300).

Almost surely, 2^81900013 is an apocalyptic number.

It is an amenable number.

81900013 is a deficient number, since it is larger than the sum of its proper divisors (10942387).

81900013 is a wasteful number, since it uses less digits than its factorization.

81900013 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 331611.

The product of its (nonzero) digits is 216, while the sum is 22.

The square root of 81900013 is about 9049.8625956420. The cubic root of 81900013 is about 434.2714947764.

The spelling of 81900013 in words is "eighty-one million, nine hundred thousand, thirteen".